c++memory-leaksld-preloadtcmallocgoogle-perftools

Why tcmalloc don't print function name, which provided via dlopen


I have next some project: main.cpp

#include <iostream>
#include <cstddef>
#include <dlfcn.h>

int main()
{
    void* handle = dlopen("./shared_libs/libshared.so", RTLD_LAZY);
    if (NULL == handle)
    {
        std::cerr << "Cannot open library: " << dlerror() << '\n';
        return -1;
    }


    typedef int (*foo_t)(const std::size_t);
    foo_t foo = reinterpret_cast<foo_t>(dlsym(handle, "foo"));


    const char* dlsym_error = dlerror();
    if (dlsym_error)
    {
        std::cerr << "Cannot load symbol 'foo': " << dlsym_error << '\n';
        dlclose(handle);
        return -2;
    }


    std::cout << "call foo" << std::endl;
    foo(10);


    dlclose(handle);


    return 0;
}

shared.cpp:

#include <cstddef>
#include <iostream>


extern "C"
{
    int foo(const std::size_t size)
    {
        int b = size / size;
        int* a = new int[size];
        std::cout << "leaky code here" << std::endl;
    }
}

and Makefile:

all:
    g++ -fPIC -g -c shared.cpp
    g++ -shared -o shared_libs/libshared.so -g shared.o
    g++ -L shared_libs/ -g main.cpp -ldl

I use tcmalloc for debug this test program, which load dynamically libshared.so:foo and execute it.run command: LD_PRELOAD=/usr/local/lib/libtcmalloc.so HEAPCHECK=normal ./a.out

The 1 largest leaks:

Why I get address 0x00007fe3460bd9ba instead of line in foo function? please help

P.s. I tried to use gdb with LD_PRELOAD=.../tcmalloc.so, but I get: "Someone is ptrace()ing us; will turn itself off Turning perftools heap leak checking off"


Solution

  • Try removing dlclose call.

    It's known issue that heap checker & profilers can't handle unloaded shared objects.